The disclosure pertains to a filter canister which treats contaminated air passing therethrough. However, it will be appreciated by those skilled in the art that the disclosure has broader applications and may be useful also in various other fluid filtering environments.
Air handling systems now frequently include filtration systems that can protect an enclosure against noxious airborne agents released in the vicinity of the enclosure. Such agents include nuclear, biological or chemical agents (known as NBC). Charcoal filters as well as paper filters (which can be provided in series with charcoal filters) are typically used in breathing apparatus for fire fighters, miners, soldiers in the field, and in many different types of industrial environments. Certain of these filter elements or cartridges are utilized in a breathing device or respirator unit which incorporates a fan for drawing or pushing air through the filter element.
Another environment utilizing filter cartridges, housed in a large assembly including a fan, is a survival shelter adapted for use as a place of refuge during warfare, industrial accidents, earthquakes, terrorism, sabotage, and the like. Such conventional shelters are provided with various filtration devices for filtering the air of the environment such as the so-called “NBC”, (nuclear, biological, chemical) filtration devices. These devices generally house a filtration cartridge, which may be an activated charcoal cartridge or the like, for filtering the air which is allowed to enter the shelter. Further, certain emergency and/or military vehicles may utilize such filters to filter air prior to circulation through a cabin of the vehicle.
In any of these environments, problems are encountered when the filter cartridges leak so that unfiltered air is allowed bypass the filter element(s). Such unfiltered air can be very hazardous to the health of those individuals breathing the air meant to be cleaned by the filtration device. Similarly, in an environment where the filter cartridge is meant to do some type of industrial filtration, any fluid (air or liquid) left unfiltered would defeat the purpose of the filtration assembly and would be similarly disadvantageous, even if it would not be hazardous to health.
Conventional filter constructions have typically included a cylindrical outer housing and a pair of end caps enclosing each end of the cylindrical outer housing. The end caps are often machined with various annular recesses on their axially inner sides for receiving a particulate filter element and a gas filter element. These are assembled within the outer housing and trapped between the end caps. Such filter elements typically share sleeves or other layers within the filter, which can make identifying issues or problems with the filter a challenge since the individual filter elements cannot readily be tested separate from each other. Moreover, since the filter elements are assembled within the outer housing, conventional filter constructions generally do not permit observation of the assembly of joints and/or interfaces within the filter that can impact filter performance. In many applications, and in particular when such filters are intended to filter air for breathing, maximizing filter construction quality and performance is desirable.